@inproceedings{irwin1967functors, title={Functors whose domain is a category of morphisms}, author={Irwin S. Pressman}, url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203212278919037}, booktitle={Acta Mathematica}, volume={118}, number={1}, pages={223-249}, year={1967}, }